The researchers suggest that it’s possible the virus could have “jumped” into humans many times, writing: “Sufficient opportunity could have arisen if there had been many prior zoonotic events that produced short chains of human-to-human transmission over an extended period.”

This week, Boris Johnson wrote to 30 million households across the country warning that the outbreak will get “worse before it gets better”.

On Sunday, a key government doctor said normal life will not resume for at least six months as all parts of the UK are placed on an “emergency footing” to tackle the outbreak.

Dr Jenny Harries, deputy chief medical officer for England, said the nation will not be in “complete lockdown” for half a year but that social distancing measures will be lifted gradually.

Meanwhile, the prime minister, who is in isolation in his flat above 11 Downing Street, revealed in a video message that some 20,000 former NHS staff have returned to help in the fight against the outbreak.

He also said the UK will get through the coronavirus crisis “together”.

“We are going to do it, we are going to do it together. One thing I think the coronavirus crisis has already proved is that there really is such a thing as society,” Johnson said.